remove unused BundlerParams and fix misleading messages

1.) There is no --properties command line arg, but the StandardBundlerParam JVM_PROPERTIES is defined and used throughout, even though it's value is always an empty map.
We should remove this parameter and it's associated resources.

2.) There are several messages when loading resources referring to class path that are misleading.

3.) the help text for --icon is wrong. Value is a path, either absolute or relative to the current directory.

4.) when an absolute path is given for main-jar, even if it is within the --input directory, there is an exception from RelativeFileSet that the says the JDK's jmods directory is not within the input directory.